This application claims priority from Japanese patent application Serial no. 2001-175001 filed Jun. 11, 2001, the contents of which are incorporated by reference herein.
1. Field of the Invention
The present invention relates to a jaw device for a jaw cylinder provided on the rotary-press folding section that ensures high printing quality by eliminating setoff on the printing surface and contamination on the paper, and preventing signatures, or folded sheets, from coming off from the jaw device.
2. Description of the Related Art
A jaw device for a folding section of a rotary press where a guided continuous paper web is cut to an appropriate length while being wound on the outer periphery of a folding cylinder, and the cut paper sheet guided along the outer periphery of the folding cylinder is caused to protrude into a jaw cylinder provided in contiguity with the folding cylinder by an insertion blade provided on the folding section, and the cut sheet is folded in parallel with the centerline of the folding section by gripping the insertion blade and the paper caused to protrude by the insertion blade is publicly known, as disclosed in Japanese Published Unexamined Patent Application No. Sho-54(1979)-63904 and Japanese Published Unexamined Utility Model Application No. Sho-60(1985)-193365.
Japanese Published Unexamined Patent Application No. Sho-54(1979)-63904 discloses a jaw device comprising a fixed jaw provided on the leading-end side wall edge in the rotational direction on an opening on the outer periphery of the jaw cylinder that is disposed at a location facing an insertion blade of the folding cylinder in the neighborhood thereof, a movable plate that is provided facing the fixed jaw in the opening in such a manner as to be movable between a position at which the paper is gripped and a position at which the paper is not griped so that the paper caused to protrude by the insertion blade can be gripped between the movable plate and the fixed jaw, and a strip made of a rubber elastic material that is provided protruded from a surface of the movable plate on which the paper caused to protrude by the insertion blade and the insertion blade is gripped so that the paper is gripped between the strip and the fixed jaw (herein after referred to as a xe2x80x9cfirst prior art.xe2x80x9d)
In the full-text specification of Japanese Unexamined Published Utility Model Application No. Sho-60(1985)-193365, a jaw device comprising a fixed jaw provided at the tip of the rear-side wall in the rotational direction in the opening on the outer periphery of the jaw cylinder that is disposed facing the folding-cylinder insertion blade in the neighborhood thereof, and a movable plate made of a flat plate that is provided facing the fixed jaw in the opening in such a manner as to be movable between a position at which the paper is gripped and a position at which the paper is not gripped so that the paper caused to protrude by the insertion blade can be gripped between the movable plate and the fixed jaw is disclosed (hereinafter referred to as a xe2x80x9csecond prior art.xe2x80x9d)
Furthermore, the full-text specification of Japanese Unexamined Published Utility Model Application No. Sho-60(1985)-193365 discloses a jaw device comprising gripping means having a fixed jaw as shown in the second prior art and a movable plate made of a flat plate, a pin provided passing through the movable plate and facing the fixed jaw for forcing the paper caused to protrude by an insertion blade onto the fixed jaw, in addition to the movable plate, and a leaf spring for transmitting a pushing force to the pin; the insertion blade notched at a position facing the pin (hereinafter referred to as a xe2x80x9cthird prior art.xe2x80x9d)
The jaw device, on the other hand, usually has a recoiling member, such as a spring, on a support member on the side of the movable plate so as to allow for differences in the thickness of the paper gripped by the fixed jaw and the movable plate, and eliminate the loosening of the grip caused by pulling the insertion blade off the jaw device.
In the aforementioned prior-art techniques, the continuous paper web guided by the outer periphery of the folding cylinder in such a manner that the leading end of the web is held by a holding mechanism provided on the folding cylinder, and guided along the outer periphery of the folding cylinder while being wound around the outer periphery of the folding cylinder. Next, the web is cut to predetermined lengths by a cutting mechanism. The cut sheet is then guided along the outer periphery of the folding cylinder, and caused to protrude toward the inside of the jaw cylinder by the insertion blade provided on the folding cylinder while the leading end of the web is released from the held state at an appropriate position.
The protruded insertion blade and the paper are gripped by the fixed jaw and the movable plate in the opening of the jaw cylinder facing the insertion blade.
At this time, the strip made of an elastic material provided on the paper-gripping side surface of the movable plate, in the first prior art, keeps forcing the paper in between the insertion blade and the strip as the strip is compressed by the angular displacement of the movable plate.
Next, the insertion blade of the folding cylinder is extracted from between the fixed jaw and the movable plate, and the cut sheet is folded in parallel with the centerline of the folding cylinder.
When the insertion blade is extracted, a gap is produced between the paper caused to protrude by the insertion blade and located on both sides of the insertion blade. This gap is closed by the repulsive force of the elastic material strip that is compressed to hold down the paper as well as by the action of the repulsive member provided on the side of the movable plate, and the paper is completely gripped by the fixed jaw and the movable plate of the jaw cylinder.
In the second prior art, when the insertion blade and the paper are gripped by the fixed jaw and the movable plate and then the insertion blade is extracted, a gap is produced between the paper protruded by the insertion blade and located on both sides of the insertion blade. This gap is closed by the action of the repulsive member provided on the side of the movable plate, and the paper is tightly gripped by the fixed jaw and the movable plate of the jaw cylinder. Thus, the cut sheet is folded in parallel with the centerline of the folding cylinder.
In the third prior art, the fixed jaw and the movable plate grip the insertion blade and the paper on both sides of the insertion blade, and the paper between the fixed jaw and the movable plate is forced directly onto the fixed jaw with a pin by the repulsive force generated by the deflected leaf spring.
Next, when the insertion blade is extracted, a gap is produced between the paper protruded by the insertion blade and located on both sides of the insertion blade. This gap is closed by the action of the repulsive member provided on the side of the movable plate, and the paper is completely gripped by the fixed jaw and the movable plate of the jaw cylinder. The pin forcing the paper by the repulsive force of the leaf spring forces the paper onto the fixed jaw, and the cut sheet is folded in parallel with the centerline of the folding cylinder.
As described above, the paper folded by the prior-art jaw device then rotates the jaw cylinder as the paper is gripped by the jaw device of the jaw cylinder. The paper is guided along the outer periphery of the jaw cylinder with the rotation of the jaw cylinder, released from the jaw device at an appropriate position, and delivered to the discharge mechanism in the downstream side.
The aforementioned prior-art techniques have several problems to be solved. In the first, second and third prior-art techniques, when the insertion blade causes a cut sheet to protrude in between the fixed jaw and the movable plate of the jaw cylinder, the paper interposed between the fixed jaw and the insertion blade is folded while being ironed by the insertion blade and fixed jaw without finding space to escape, leading to contamination on both sides of the paper. In addition to this, the overlapped paper sheets are pressed each other, resulting in a setoff, or the transfer of printed images to the opposing printing surfaces that leads to contamination of the paper.
Furthermore, as the jaw cylinder gripping the cut and folded paper is rotated and the cut and folded paper is guided along the outer periphery of the jaw cylinder with the rotation of the jaw cylinder, the paper moves along with one end folded and gripped and the other free end being trailed toward the upstream in the rotational direction of the jaw cylinder. Thus, a force in the opposite direction to the rotational direction of the jaw cylinder acts upon the jaw proper.
In the first prior-art technique, this force tends to separate the movable plate away from the fixed jaw, resisting the force of the repulsive member provided on the movable plate side, causing a gap between the fixed jaw and the gripped paper. In the second prior-art technique, an end of the folded and gripped paper acts like a lever with the fixed jaw as a fulcrum to prize open the movable plate in the direction away from the fixed jaw resisting the force of a repulsive member provided on the movable plate side. Thus, a coming off of paper could result in both the prior-art techniques.
In addition, when the fixed jaw and the flat movable plate grip the insertion blade and the paper, as in the second prior-art technique, there is nothing to resist the slip of paper on both the fixed jaw and the flat movable plate. As a result, the paper may be pulled out of the jaw cylinder, together with the insertion blade, leading to disruption in paper folding operation.
It is an object of the present invention to provide a jaw device for a rotary-press folding section which eliminates the contamination of paper surfaces caused when an insertion blade causes a paper web being cut to protrude in between a fixed jaw and a movable plate
It is another object of the present invention to provide a jaw device for rotary-press folding section which prevents paper from being disrupted when the insertion blade extracts the paper from the jaw device, and from coming off when a jaw cylinder gripping the folded paper is rotated to guide the paper to the succeeding process.
In the disclosed embodiments, there is provided on a jaw cylinder a jaw device in which a cutting cylinder, a folding cylinder and a jaw cylinder a provided in parallel with each other in a folding section of a rotary press, a continuous paper web guided in between the cutting cylinder and the folding cylinder is further guided along the outer periphery of the folding cylinder, with the leading end thereof held by a holding mechanism provided on the folding cylinder and wound around the outer periphery of the folding cylinder by the rotation of the folding cylinder, and cut into a predetermined length by the collaboration of a cutting mechanism provided on the cutting cylinder and the folding cylinder, the cut paper sheet being guided to an appropriate position along the outer periphery of the folding cylinder, with the leading end of the cut paper sheet released from the held state and caused to protrude into the jaw cylinder by an insertion blade of an insertion blade mechanism provided on the folding cylinder, both the insertion blade and the paper caused to protrude by the insertion blade being gripped, and the cut paper sheet being folded in parallel with the centerline of the folding cylinder; the jaw device having such a construction that the jaw device comprises at least one opening provided in parallel with the axial line on the outer periphery of the jaw cylinder facing in close vicinity of the insertion blade of the folding cylinder, a jaw provided in parallel with the opening and comprising at least one thin plate made of an elastic material, and gripping means comprising a movable plate made of a thin elastic material provided in parallel with the jaw that can move the insertion blade and the paper caused to protrude by the insertion blade from a position at which the paper is gripped to a position at which the paper is not gripped, so that the insertion blade of the folding cylinder and the paper caused to protrude into the cylinder by the insertion blade can be gripped by the jaw made of a thin elastic material and folded.
A slip stopper made of a material having a large friction coefficient is provided on any one or both of the surface of the movable plate of the gripping means at which the paper is gripped, and the surface of the jaw at which the paper is gripped.